[PATCH] drm/plane-helper: Skip prepare_fb/cleanup_fb when newfb==oldfb

[Rodrigo Vivi]

Thanks for the fix.

Tested-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

On Mon, Jan 19, 2015 at 8:31 AM, Matt Roper <matthew.d.roper at intel.com> wrote:
> When commiting a plane update where the framebuffer doesn't change, we
> can skip the prepare_fb/cleanup_fb steps.  This also allows us to avoid
> an unnecessary vblank wait at the end of the operation when we're just
> moving a plane and not changing its image (e.g., for a cursor).
>
> At the moment, i915 is the only upstream driver using the transitional
> plane helpers, and thus the only driver affected by this change.
>
> Reported-by: Jeremiah Mahler <jmmahler at gmail.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88540
> Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
> ---
>  drivers/gpu/drm/drm_plane_helper.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c
> index f24c4cf..7a5814a 100644
> --- a/drivers/gpu/drm/drm_plane_helper.c
> +++ b/drivers/gpu/drm/drm_plane_helper.c
> @@ -435,7 +435,8 @@ int drm_plane_helper_commit(struct drm_plane *plane,
>                         goto out;
>         }
>
> -       if (plane_funcs->prepare_fb && plane_state->fb) {
> +       if (plane_funcs->prepare_fb && plane_state->fb &&
> +           plane_state->fb != old_fb) {
>                 ret = plane_funcs->prepare_fb(plane, plane_state->fb);
>                 if (ret)
>                         goto out;
> @@ -456,6 +457,13 @@ int drm_plane_helper_commit(struct drm_plane *plane,
>                         crtc_funcs[i]->atomic_flush(crtc[i]);
>         }
>
> +       /*
> +        * If we only moved the plane and didn't change fb's, there's no need to
> +        * wait for vblank.
> +        */
> +       if (plane->state->fb == old_fb)
> +               goto out;
> +
>         for (i = 0; i < 2; i++) {
>                 if (!crtc[i])
>                         continue;
> --
> 1.8.5.1
>
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-- 
Rodrigo Vivi
Blog: http://blog.vivi.eng.br